Download - Macs LightIntro Tutorial

Transcript
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    Vray for Rhino Interior Lighting

    This Tutorial was adapted from the website below. It was edited into its current form and sections added by Glenn Hill.

    http://macdesignstudio.wordpress.com/2011/04/28/introduction-to-vray-lighting/

    NOTE: The reason to implement the lights before adding material is simple, with good lighting the materials will fall into their own. Once the lighting is set correctly, you will then have a realistic feeling for what the materials are doing and how they react to subtle changes. Then add an exterior light to simulate the sun coming in from each window. To do so, I use the Sunlight tool that comes with Vray for Rhino. This allows the user to have advanced control over the exact sun angle given a particular time of day and geographic location, or you can manually place the angle of the sun if specifics arent important.

    NOTE: In the file rendered below the glass surfaces have been turned off because they have no transparent material applied at this time and a Default Material (RGB: 128,128,128) was added to all the objects in the scene.

    Light Intro_Tutorial Model provided by Glenn Hill

    NOTE: Another method to insure you do not get any material interference, is to add a neutral material in the Material Override channel of Global Switches in the VRay Option Settings. Check the Overrride material box under the Global Switches tab as shown in the image below. In order to allow the light to come through the openings hide window glass or turn off the layer the glass in on in the Rhino model. The Material Override will override all materials including the glass.

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    Override Material with color over 128-128-128, a medium grey

    1. Place Sunlight in the scene. 2. Type Sunlight in the Command Line. 3. Sunlight Dialogue box will appear. 4. Set the Month, Day and Time of the Sunlight so the light will shine through the windows. You may choose to us a

    MANUAL light settings so you can direct the light where you want it. 5. Click OK Button. 6. Place the Sunlight ICON in the scene. Set it off to the side out of the way. Where you put the icon has no impact on

    the light. 7. Render the scene.

    Sunlight: Dallas, Texas 09/20/11 @ 10:00a

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    NOTE: It should be noted that this Sun lighting system works only when using the Vray Physical Camera in the Camera settings.

    GLENN COMMENT: Matt in his tutorial uses this procedure to add more light through the windows. If the sunlight is at the right intensity, the camera settings are set correctly, and the glass material is correct there is no real need to do this step. You might leave this step off first then if you do not get adequate light in the space come back and add these lights.

    8. The next step is to add rectangular lights at the openings to supplement the sunlight system. This helps to create additional light as well as add a bit of realism to the scene by focusing more light at the openings. To do so, create a rectangular light that is slightly larger than the opening, ensuring that the light is pointing into the room as shown below.

    9. Select the Light. Click on Properties Tab roll down and select Light instead of Object. 10. Multiplier = .5. Depends on a few factors (camera settings, and size of the light mostly) 11. Click on Light Portal. This tells the program that the light is to be used

    to supplement the existing light from the exterior. 12. Click on Invisible. So you can see through it and see the exterior of our scene. 13. Turn OFF: Double Sided. In this case, we dont need to have the light be double sided because were only interested

    in focusing the lights energy to the interior of the scene.

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    14. VRay> Options> Global Switches Tab. 15. Check Lighting. We want to ensure that lighting is checked, letting the program know that it needs to calculate the

    lighting. 16. Uncheck Hidden Lights. So any hidden lights in the scene will not be used in the rendering. 17. Uncheck Default Lights. We do not want the Rhino Default Lights to be used only the lights that we have placed and

    have control over.

    Global Switches Tab

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    18. VRay> Options> Camera Tab. 19. Check Physical Camera. If we forget to check this box, the scene will be WAY too bright because were not allowing

    the calculations to compensate for the incredible intensity from the sun. NOTE: For those who have used a digital SLR camera or a film camera should quickly recognize the controls over the physical camera. Here you have the ability to control the cameras shutter speed, the F-stop number, and the film speed. These three numbers work in conjunction with each other to create how the camera compensates for the exposure of the lighting. This may take some time to get comfortable with if you have never used a SLR camera before, but the Vray manual has a very thorough explanation of how each of these controls works. It can be found at ChaosGroup.com under the software and support tab.

    Camera Tab

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    20. VRay> Options> Output Tab. 21. Overide Viewport. Set resolution of images to desired output.

    NOTE: The Output tab allows a user to override the size of the image that they wish to output. If, for example, I know that I need an image that is 1500 pixels by 800 pixels, this is the place to input that information. It also allows a user to obtain the aspect ratio from the existing scene for easy scaling, by first selecting the Get View Aspect, locking the ratio, and then changing the pixel size. This is useful if a user wants to ensure what they see on the screen is what is rendered for a given size. If I set up my scene and like how it looks on my screen, Ill use this technique and then tell the program that I need a maximum of (for example) 1500 pixels wide. However if Im simply doing test renders, the output size isnt an issue yet.

    Output Tab with ability to change rendering size

    22. VRay> Options> Environment Tab: GI (skylight)

    NOTE: The Environment tab gives the user the ability to create the environmental lighting (not the direct sunlight, but the light from the sky) and control how it is handled in the scene. Because we have created a sunlight system, its possible to link the position of the sun light to the environmental light. By linking the two, we will get a reddish light as the sun approaches the horizon as occurs in nature, as the light comes closer to noon, the environmental light will become more blueish. To link the sunlight position to the environmental lighting, select the little m next to the GI (skylight) check box.

    23. Select the little m next to the GI (skylight) check box.

    24. When this is selected, a new Map Texture Editor dialogue box will appear. 25. Set Type from none to Sky. 26. Turn OFF: Overide Suns Parameters. 27. Set Sun-light Source: SUN. 28. Click APPLY.

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    NOTE: Before selecting apply, we must make sure that the program knows which light source we want the sun to be. Select the button next to Sun-light source. A new pop up menu appears and now allows us to select the sunlight we previously created. If we leave this at Default, we will not create a link between the sun light and the environmental light. Once we select the proper light, click apply, to get back to the the Vray Texture editor. Make sure that you unselect the check box next to Override Suns parameters and finally click apply. We have now created a link between the light from the environment (in this case the sky) and the suns position in the sky.

    29. VRay> Options> Environment Tab: Background.

    NOTE: The next option in the environment tab is the Background. We can follow the same process that we just went through to add a background that matches the suns position in the sky, or we can add a background image if we have a jpeg that we want to use as a background. This can be helpful if we have a site photo, a stock image of a nice sky with some clouds, etc. Since I am creating an imaginary scene, Im going to apply the link to the suns position as previously mentioned following the same processes. At the end of this process your Environment tab should look similar to that below.

    Completed Environment Tab with mapped GI and Background

    30. VRay> Options> Indirect Illumination Tab: GI: Turned On. 31. Primary Engine: Irradiance Map. Secondary Engine: Light Cache.

    NOTE: The next tab well talk about it the Indirect Illumination tab. First, ensure that the box under GI is turned on. The allows the light waves to bounce off of geometry and give reflected light, ensuring that light bounces off the floor and continues to bounce and light the scene. If this isnt turned on, the only thing we will see in our scene is the direct light from our light sources which will cause a very harsh and yucky (yes, thats a technical term) lighting results. Next we get to select what types of rendering engines we will use. These deal with the way that the program calculates how the light reacts in our scene. A good start is to use the Irradiance Map (IR Map) as the primary engine and the Light Cache (LC) as the secondary engine. I have found that these two in combination give me the best quality and the lowest render time.

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    Indirect Illumination tab

    32. VRay> Options> Irradiance Map Tab: For test renders I use the following values.

    IR Map settings

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    VRay> Options> Light Cache Tab: For test renders I use the following values.

    NOTE: The scene the subdivs can be between 100 (quicker, less accurate) and 500 for tests. You will want to increase them to at least a 1000 for a final render.

    LC settings - note: subdivs can vary between 100 and 500 for test renders.

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    Render the Image.

    NOTE: We can now run a quick test render to ensure that our exterior lighting is working correctly and with a short render time we get decent results. Its a bit grainy, but we will take care of that later. At this point, were strictly focusing on the lighting. You should notice a blueish tint on the floor close to the windows as a result of linking the environmental lighting to the suns position. This is what we would expect from natural sunlight, during the middle of the day.

    Test Quality Rendering - Sunlight Only Turn on Gamma.

    ADDING INTERIOR LIGHT Sconces and Lamps.

    NOTE: We can now continue adding lights to our scene. For wall sconces and lamps, add double sided rectangular lights because 1) they are faster at render time and 2) the light will come out of a sconce and lamp primarily from the top and bottom (yes, I know the shade will glow, but you can take care of this with a double sided emissive material). For down lights you should use either spot lights if you need the conical shape of the light or just use a rectangular light, single-sided. If there are door openings to other rooms add a rectangular light at the ceiling level of the adjacent room. This will add a slight amount of light to the scene.

    33. Add Rectangular Light. Add a rectangular light inside the lamp shade.

    34. Place the light near the top of the lampshade and make sure it does not intersect the lamp shade.

    35. Multiplier = 3000 [Lumens]. Set the lights intensity to Lumens, but you could use a multiplier. A multiplier would probably have to be set to 20 to get adequate light from a small triangle. Of course adjust the light level to reflect the desired lighting input.

    36. Turn On: Invisible. Double Sided. 37. The rest of the settings can be left as DEFAULTS. 38. Later you may want to Turn Off: No Decay to get a more

    natural lighting condition.

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    Sunlight with lamp - Notice light coming out of the top of the shade Turn On Gamma.

    NOTE: Below are three renderings of the above scene. With Different Envrironment lighting conditions turned on and off. This may give you a better understanding of the role of each these light components - Sunlight, GI (skylight) and Background.

    NO Sunlight. In this first rendering the GI (skylight) and background light Options have been left on and only the direct Sunlight has been turned off. Notice there is still significant light being provided by the Sky and Background. If you remember each of these components has a SKY map assigned to their channel. Also, remember because of the time of day and the GI (skylight) is linked to the Sunlight System the light is tinted a slight blue. Of course there are no beams of light entering the room, because the Sun has been turned off.

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    NO Sunlight or GI (skylight). The Sun and Sky have been turned off in the image below. A little light is coming from the windows because a SKY map was added to the Background channel.

    NO Sunlight, GI (skylight) or Background. Notice now the only light coming into the space is from the lamp in the corner of the room. All the indirect light is from the light bouncing off of the different surfaces. Notice the window to the far right and surface facing away from the lamp are pitch black

    NOTE: Hopefully this sequence gives you some insight into the role of these three different Environment sources of light on the scenes lighting.

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    ARTIFICIALLY LIT INTERIOR.

    To artificially light this interior space we are going we are going to first make some modifications to the Environment and add a transparent material to the Window Glass.

    1. V-Ray> Material Editor. 2. Material Editor dialogue box. Right Click. Material Workspace> Scene Materials and select Add Material> Add VRay

    Mtl. 3. Name the new material Glass-Clear. We are going to create a very simple clear glass material with a DIFFUSE,

    REFLECTION and REFRACTION channel. In the Reflection channel we will place FRESNEL map. See the settings below for complete material settings.

    4. Turn On the Window Glass Layer. 5. Assign the Glass-Clear material to the glass object. 6. Set the Texture Map to Surface. 7. IMPORTANT: TURN OFF MATERIAL OVERIDE before you render or your glass will not be rendered. 8. OPTIONS> Environment> TURN ON: GI & Background. 9. Render the Scene.

    NOTE: There is light coming through the glass from the Sky and Background. Also, you may notice a slight tint of blue in the right hand window coming from the exterior.

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    lmprove the Background. Now add a background image City Lights outside the windows. 1. Draw a rectangular surface outside the bank of windows in your scene to be used as a backdrop for the scene. 2. Make the rectangle wider than the room and twice as tall. Position the surface so the majority of the surface is below

    the room. See Image 3. VRay> Material Editor>Workspace> Scene Materials. Right Click. Add Material> Add VrayMtl. 4. Name: City_Lights. 5. Click on the Diffuse channel map button m. 6. Type: Bitmap. Click on map button m and select the City_Lights.jpg. 7. Filter: Summed Area. Uncheck Tile. 8. Uncheck: Trace Reflections and Trace Refractions and Reflect on Backside. 9. Assign this material to the Rectangular Backdrop. 10. Render the scene.

    NOTE: Move the Backdrop around until you get the image in the right location. Also if you are not getting enough light increase the GI (skylight) multiplier or change the time of day. There are a number of lighting effects that can be achieved by playing with the Sky and Background conditions.

    GI (Skylight), Background and Lamp with Glass material.

    GI (Skylight), Background and Lamp with Glass material and Backdrop.

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    Enhance the interior lighting. Now we are going to add some additional interior lights to the room to change the atmosphere of the space.

    RECESSED LIGHT.

    NOTE: There are a number of recessed lights in the ceiling of this scene. The following lighting steps cover a couple of simple ways one might light the space using this type of fixture.

    39. Add Rectangular Light. Add a rectangular light just below the can lights in the ceiling. Make sure the rectangle is not embedded into any geometry. This will create a general flood of light coming from the fixture.

    40. Make sure the light is slightly below the fixture geometry and the normal is pointing down into the room. 41. Multiplier = 1000 [Lumens]. You may adjust this according to your needs, but this is a good start. 42. Turn OFF: Double Sided and No Decay.

    NOTE: Reduce the Fixture geometry to the minimum to only the geometry which will be seen. Notice in the image below the majority of the fixture has been deleted and only two pieces of geometry are left. The Rectangular Light was placed below these Fixture components and the 4 objects and light were then made into a block and saved out of the scene file for future use.

    43. Follow the advice of the NOTE above. 44. Delete all the recessed lights from the scene. 45. Insert this new block [Fixture & Light] into the four recessed areas over the couch. 46. Render the scene. (See image Below)

    NOTE: To make the Fixture glow and an emissive material to the curved lens of the fixture. You might add a Flat Black paint color to the circular housing. NOTE: You can try replacing the Rectangular Light with a Spotlight. Place the top of the cone just below the fixture and point it down into the room. Notice how this changes the room.

    The four recessed Rectangular Lights with GI (skylight) and Background turned on.

    Light Fixture Geometry Deleted. Fixture and Rectangular Light made into a Block.

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    COVE LIGHT.

    NOTE: There is a recessed cove around the entire room. Lets assume we would like to put cove lighting up in this recess to provide a different type of lighting experience. Once again we will use Rectangular Lights.

    1. Add Rectangular Light. Add a rectangular light an inch or two down from the top of the cove. This will create a general flood of light coming from the cove. Make sure the rectangular light is not embedded into or blocked by any geometry. Use as few lights as possible this will improve the rendering speed two lights were used in this scene

    2. Make sure the lights normal is pointing down into the room. 3. Multiplier = 1000 [Lumens]. You may adjust this according to your needs, but this is a good start. 4. Turn OFF: Double Sided and No Decay. 5. Turn OFF the four recessed lights so we can see the sole impact of just the cove lights. 6. Render the scene. (See image Below)

    NOTE: To get a more balanced light in the scene another cove light was placed in the cove of the other bank of Windows out of the Cameras View. This may be a subtle difference, but a difference.

    One cove Rectangular Light with GI (skylight) and Background turned on.

    One cove Rectangular Light with GI (skylight) and Background turned on.

    Rectangular Light placed in the ceiling cove. This type of lighting is often referred to as a cove light.

    Vray for Rhino Interior Lighting